mongodb多表查詢(附帶pymongo執行個體)

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mongodb有$lookup可以做多表查詢

舉個例子

db.orders.aggregate([ { $lookup: {  from: "inventory",  localField: "item",  foreignField: "sku",  as: "inventory_docs" } }])

上面的代碼意思是，從order表中取item欄位作為inventory表中sku的查詢條件，然後把資料儲存到inventory_docs欄位

等價於db.inventory.find({‘sku‘:"item"})

下面用pymongo實現

from pymongo import MongoClientdef test():    client = MongoClient()    db = client[db_name]    db[‘orders‘].aggregate([{‘$lookup‘:{‘from‘: "inventory", "localField": "item", "foreignField": "sku", "as": "inventory_docs"}}])

這樣就實現了上述的效果了

mongodb多表查詢(附帶pymongo執行個體)